Dyeing of keratin fibres, particularly hair, is known. The desire to alter the colour of hair is not a facet of modern times. Hair colour is altered to accommodate changes in fashion, style, and personal preference. However, obtaining good colouring and wearability without undesirable side effects to the hair and skin, remains an elusive goal. A suitable method of colouring hair is through oxidative dyeing. A variety of colours may be obtained, including yellows. Although the inventors choose not to speculate on the veracity of the adage according to which reputedly “blondes have more fun,” they do recognize that yellow dyes themselves are desired.
Yellow dyes, particularly those used in colouring hair, should provide good colouring, including intensity of colouration and/or fastness, and be able to perform in spite of external agents, such as light, particularly sunlight, adverse weather conditions, washing and styling, permanent waving, perspiration, and/or friction. Such dyes should also be favourable as to toxicology and dermatology. They should be useful in providing a wide range of shades when combined with other ingredients and process stages, too.
The use of 2-aminophenol (also known as ortho-aminophenol or OAP) and some derivatives thereof, for yellow dyeing of keratin typically by self coupling is known. For example, U.S. Pat. No. 4,396,392 (Wella, AG) discloses 2-amino-5-methyl-phenol and WO 02/058,657 (Clairol, Inc.) discloses 2-(amino or amino substituted)-5-methyl-phenol, each for use in providing yellow colour, alone and in combination with other colouring agents.
However, many previous oxidative dye compounds and combinations of such compounds resulting in yellow colourations have demonstrated poor wearability and stability to light, and some have recently experienced objections to their use from a toxicological standpoint. OAP, in particular, has been found to provide poor yellow, e.g. with off-tones. One alternative approach has been to use direct non-oxidative dyes alone or in combination with lessened quantities of oxidative dyes. However, this approach has been found to result in poor wash fastness upon shampooing, among other undesirable effects. Thus, there remains a need to provide further oxidative dye alternatives to known dyes, preferably yellow dyes, and compositions for dyeing of hair comprising them, that produce good colouration, preferably a bright yellow colouration, that exhibit good dye uptake by the hair, are useful in providing shades or colours which are stable over a reasonable period of time, provide good wash fastness and wearability, good selectivity, do not undergo significant change on exposure to light, shampooing or acid perspiration, and/or exhibit a favourable safety profile.
It has now been surprisingly found that by placing substituents in the 5 and 6 positions of 2-amino phenols and 2-(substituted amino) phenols, compounds exhibiting one or more of the aforementioned desirable qualities may be provided. Without being bound by theory, it is believed that the addition of such substituents in these positions may provide similar improved yellow colour formation and wash fastness with improved toxicology via the steric hinderance of the phenol functionality (—OH) vs previous 2-aminophenols and 2-aminophenol derivatives.
A number of 5, 6-substituted 2-amino phenols are described in W002083624, U.S. Pat. No. 6,262,113, WO00/61580 and WO04/037218 the latter of which describes 4-amino or substituted amino-3 hydroxy-phenyl)-alkynitrile compounds.